Spherical-Spherical

Library

Joints/Massless Connectors

Description

The Spherical-Spherical block represents a composite joint composed
of two spherical joint primitives.
The Body coordinate system (CSs) on either side
of the Joint are connected to the spherical primitives. The primitives
are separated spatially by a vector of constant length but variable
direction connecting the two Body CS origins.

Massless Connector Between Spherical and Spherical
Joints

Satisfying Joint Requirements

A Joint block represents the relative degrees of freedom between
two bodies, not the bodies themselves.

You must connect any Joint block to two and only two Body blocks,
the base and the follower. All Joints have
a default of two connector ports for
these connections, defining the direction of joint motion (base to
follower). You connect each side of the Joint block to these Body
blocks at a Body coordinate system (CS)
point.

You specify the joint primitive axes, if any, in the Joint dialog.

You cannot connect an Actuator or Sensor to a Massless Connector.

Assembly Restrictions on Massless Connectors

Both joint primitives are assembled but
spatially separated. That is, the connected Body CS origins must not
be spatially collocated points.

The distance separating the two ends of the connector is computed
automatically from the Body CS origins to which the Joint is connected.
This distance (the magnitude of the vector between the Body CS origins)
remains fixed at its initial value during the simulation. This initial
value must be nonzero.

Dialog Box and Parameters

The dialog has two active areas, Connection
parameters and Parameters.

Connection Parameters

The base (B)-follower (F) Body sequence determines the sense
of positive motion. Positive rotation is the base or follower pivoting
as shown by the motion figure in the Spherical block
reference page.

Parameters

Switch between the Axes and Advanced tabs.

Axes Tab

The entries on the Axes tab
are automatic. They specify the orientation of the spherical DoFs
that the Spherical-Spherical represents.

Name

This column automatically displays the name of each primitive
joint contained in the Joint block. For Spherical-Spherical, there
are two spherical primitives, labeled S1 and S2,
connecting to base and follower, respectively.

Primitive

This column automatically displays the type of each primitive
joint contained in the Joint block. For Spherical-Spherical, there
is only one primitive type, labeled Spherical.